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Token Engin-nerd
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3,414 Posts
Discussion Starter #1
Well I got tired of people that think they know what theyre talking about and decided to cut through the BS about the difference in bias ratio between the Torsen and Quaife torque biasing diffs. So I contacted the manufacturers. I asked each about the diffs they have for the Getrag and MTX-75, and even asked Quaife about their ib5 unit. Here is what they had to say:


Quaife said:
We do not use or quote TBR figures as they don't really mean much to anyone. The TBR is a very difficult thing to measure (we know this from our work with OEM diffs) and actually not very useful.

Essentially the TBR is a complicated way of comparing the helix angle of the internals (sun gears and pinions) and the vast majority of our diffs have the same angle internals although some of the very large and very small diffs have different angles. A few diffs have options (eg QDF9U) as they are used in different applications, i.e. QDF9U (31dg) in a Honda Civic Type R or QDF9U/23dg in an Ariel Atom. If you put a standard QDF9U (31dg) in an Atom (very light mid engined car) the diff would push too hard for the amount of grip at the front.

Now i have explained my position, the answer to your question is around 2.1 on drive and 1.9 on coast (for a 31dg diff which is most of them). These figures were measured and produced by Getrag Ford using the new Focus RS diff which is a modified M66 gearbox (QDF13J).

The 3 diffs you have listed are all 31dg. Good luck

Torsen said:
The bias ratio for both units is around 2.1:1. The Torsen stays static or
does nothing until the unit reaches a torque imbalance from one wheel to the
other. This imbalance must exceed the bias ratio of the unit at which point
it becomes dynamic and starts to differentiate. The unit does not float
between 1:1 to 2.1:1. It resembles an open differential until it becomes
dynamic and differentiates.

Thanks for the question and hope this explanation helps!

So they have the SAME torque ratio at which they will begin to bias torque.




...And for Pete's sake they are not LSD's. [screwy]
 

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Max8
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2,858 Posts
illinipo, you are my hero! I always wanted to say that these were not LSDs but didn't want to handle the bullcrap I was going to get without information. You just made my day.
 

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Token Engin-nerd
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3,414 Posts
Discussion Starter #3
cool [thumb]

just trying to keep the misinformation around here to a minimum.
 

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FOCUS REVOLUTION
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2,872 Posts
well i know there not real "lsd" but they are better than stock
 

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Token Engin-nerd
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3,414 Posts
Discussion Starter #7
Theyre also better than an LSD in certain situations like digging out of tight corners in autocross.
 

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Dragon Warrior
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309 Posts
oh noes too much gas got me into trouble.......and a little more is going to get you out :p

oh the beauty of quaife and torsen!
 

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Token Engin-nerd
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3,414 Posts
Discussion Starter #10
nope they send equal torque like an open diff until the ratio is over 2.1:1 left to right or right to left, at which point they start biasing torque to the most grippy wheel.
 

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Broken cars s[:)][:)][:)] :(
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18,832 Posts
wow...very nice man...very nice
 

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Focus "Sleeper"
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1,619 Posts
Wow. Confusing stuff.

SO what I understand from this is that both of these units will work the exact same? SO what is the difference between the two? Terribly sorry for the super newb question...
 

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Token Engin-nerd
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3,414 Posts
Discussion Starter #13
the quaife has a lifetime warranty and costs more.
 

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Max8
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2,858 Posts
Newb question here also, but then... What would be the phantom grip considered then?
 

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Token Engin-nerd
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3,414 Posts
Discussion Starter #15
The phantom grip is a limited slip since it uses friction to hold the two wheels closer to the same rotational speed.
 

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Max8
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2,858 Posts
just what I thought, but is it a full LSD or just like a begginers lsd?
 

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Token Engin-nerd
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3,414 Posts
Discussion Starter #20
one reason is they use the stock spider gears which are known to break even without all that extra force on them
 
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